After our checking the influence of memory subsystem parameters on performance of the Core 2 Duo platform in general, we now want to test a few DDR2 SDRAM kits that you can actually use in your system. Let's put theory to practical use, so to say.
Memory manufacturers are currently offering an abundance of products varying in the default frequency as well as timings. But besides the default mode specified by the manufacturer, the modules can be used in other modes as well. Memory that is meant to work at a high frequency can also do well at a relatively low frequency but with aggressive timings. So, judging different memory kits only by their specifications is basically wrong. Besides default characteristics, it is useful to know how memory performs in modes other than those declared by the manufacturer. That's exactly what we are going to do now - to check out some popular overclocker-friendly memory kits under non-standard conditions.
Right now, dual-channel DDR2 SDRAM kits consisting of two modules with a total capacity of 2GB seem to be the most interesting product. 1GB memory kits aren't a good choice anymore for top-end and midrange systems as we have stated in our earlier review. As for the memory frequency, modules rated for 800MHz and higher should be considered optimal for overclockers today.
In this review we'll focus on 2GB DDR2 SDRAM kits capable of working at a frequency of 1GHz and higher. We'll see what such kits are capable of in the Core 2 Duo platform that is winning more users with each day.
We used two mainboards for this test: an ASUS P5W DH Deluxe on the Intel 975X Express chipset and an ASUS P5B Deluxe on the Intel P965 Express. We had to use two mainboards because each has certain peculiarities when it comes to working with the memory subsystem. The BIOS Setup of the ASUS P5W DH Deluxe offers limited control over secondary memory timings, which affects an attempt to overclock DDR2 SDRAM above 1GHz. In other words, not all modules are capable of revealing their full potential on this mainboard when overclocked to frequencies of 1.0 to 1.1GHz. Users of this mainboard recommend sticking to the automatically assigned values for the memory subsystem settings, but we couldn't follow that advice in our overclocking tests. The other mainboard, ASUS P5B Deluxe, offers much more memory-related settings in its BIOS Setup, but is overall less stable than the ASUS P5W DH Deluxe when you choose aggressive memory timings.
To make sure the tested memory is stable in a particular mode, we used three utilities: Memtest86, S&M and Prime95. Quite a lot of popular performance benchmarks, even those that utilize memory heavily, run without problems under conditions that prove to be not stable if tested by special-purpose utilities. So, we use the mentioned three programs to be absolutely sure that the tested memory is stable at a given frequency and with particular timings.
We tested the memory modules at the voltage which is specified by their manufacturer as the default one.